Oral fat tolerance testing identifies abnormal pancreatic β‐cell function and insulin resistance in individuals with normal glucose tolerance

Abstract

Aims/Introduction: Insulin sensitivity and b-cell function are affected by lipid metabolism disorders, even before the onset of type 2 diabetes. People are in the postprandial state most of the time. Therefore, identifying postprandial hyperlipemia is important. This study aimed to assess patients with abnormalities in lipid metabolism, but with normal glucose tolerance, using oral fat tolerance testing (OFTT) to identify defects in insulin sensitivity and b-cell function. Materials and Methods: We included 248 volunteers with normal glucose tolerance who underwent OFTT. They were divided into three groups in accordance with their fasting and 4-h postprandial triglyceride (TG) concentrations. Their lipid concentrations during OFTT were compared. The disposition index (DI) was applied to estimate b-cell function, and the Matsuda insulin sensitivity index (ISI M ) was used to assess insulin sensitivity. We used multiple linear regression analysis to estimate the relationships of fasting and postprandial TG concentrations with b-cell function and insulin sensitivity . Results: The changes in TG concentrations during OFTT were more marked than those in low-density lipoprotein-cholesterol, high-density lipoprotein-cholesterol or total cholesterol concentrations. As lipid metabolism deteriorated, the ISI M and the DI gradually decreased. Multiple linear regression analysis showed that fasting and 4-h postprandial TG concentrations affected LnISI M and LnDI. Conclusions: In individuals with normal glucose tolerance, b-cell function and insulin sensitivity gradually decrease with a deterioration in the lipid profile. Not only fasting TG, but also postprandial TG concentrations are independent risk factors for impaired b-cell function and insulin resistance.

Metabolic Effects of Brown Adipose Tissue Activity Due to Cold Exposure in Humans: A Systematic Review and Meta-Analysis of RCTs and Non-RCTs

“…Therefore, for a more comprehensive understanding of the beneficial effects of CE on glucose homeostasis, gold-standard methods such as the Botnia Clamp will be very important, which is the gold standard to assess beta cell function and insulin sensitivity. Considering lipid homeostasis, an OFTT has been known to determine intestinal fat metabolism in rodents and humans by consumption of high-fat meals [ 75 , 78 ], and monitoring blood TG levels could count as a complementary method to the monitoring of fasting FFA and TG.…”

Serum Gamma Glutamyltransferase: A Biomarker for Identifying Postprandial Hypertriglyceridemia

“…Additionally, the postprandial 4-h TG level is a distinct risk factor for insulin resistance and decreased islet beta cell function. 30 Since most people only fast for a few hours daily, detecting lipids in a non-fasting state relative to a fasting state may better reflect an individual’s comprehensive metabolic status. 8 , 31 As indicated in a 2019 statement on PHTG, 28 when the fasting TG concentration ranges from 1–2 mmol/L, OFTT detection of PHTG should be considered for assessing PHTG and predicting metabolic risk.…”

A bibliometric analysis and visualization of literature on non-fasting lipid research from 2012 to 2022

“…The triglyceride-insulin-glucose-glucagon-like peptide-1 model was built to assess glucose, insulin, and incretin responses following a high-fat meal ( 49 ). The OFTT can help patients identify insulin sensitivity impairments, insulin resistance, beta-cell dysfunctions and secretion disorders of gut hormones, including glucose-dependent insulinotropic polypeptides and glucagon-like peptide-1 ( 21 , 50 ).…”

“…Non-fasting lipid metabolism is not only associated with cardiovascular disease (CVD), but also with diabetes ( 17 ), metabolic syndromes ( 18 ), non-alcoholic fatty liver disease ( 19 ), and polycystic ovarian syndrome ( 20 ) among others. The pathophysiological processes associated with postprandial metabolic responses have a connection with insulin resistance ( 21 ), oxidative stress ( 22 ), endothelial dysfunctions ( 23 ), and gut microbiota ( 24 ) among others. Nutrition ( 25 ), physical exercise and medication ( 26 ) play an important role in prevention and treatment strategies.…”